This invention relates to vehicle suspension systems and, more particularly, to powered, automatic control system for causing the rear axles of a vehicle having a long wheel base (e.g., trucks, trailers, and buses) to track around sharp corners. In this respect, this invention is an improvement over the invention disclosed in U.S. Pat. No. 5,220,972, issued to the present inventor on Jun. 22, 1993 and entitled "Self-Tracking, Rear Vehicle Suspension System For Trucks, Trailers and Buses", the entire disclosure thereof being incorporated herein by reference.
The invention of the '972 patent teaches the making of self-tracking rear axles through angling of the torsion rods coupled with means for permitting lateral deflection of the suspension type employed on the vehicle (e.g., widening of the spring hangers on a vehicle employing a leaf-spring type suspension). More particularly, the forward ends of each pair of laterally spaced torsion rods are moved inwardly toward each other to create separate reaction forces which cause the associated axle to pivot with respect to the vehicle centerline in a direction away from the turn during cornering. Consequently, the rear tires rotate closely along the line of travel of the front tires such that the rear tires track around the corner and, as such, the driver can safely negotiate a turn without having to use two lanes of traffic as drivers of such vehicles normally do when making sharp turns.
The present invention improves upon the '972 system by adding power controls which automatically respond to cornering of the vehicle by applying a controlled, measured force against selected points of the vehicle's suspension system which further assist in pivoting the rear axle(s) in the appropriate direction, thereby causing the respective rear tires to self-track into the turn, in both forward and rear directions of travel. The invention also has applications in specialized, military-type vehicles having multiple steering axles at both the front and rear of the vehicle.